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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6e3c56951bee12bdeb76c8ba3e6164aa8c4e0b57ef53de5a43abfe690877573' 
  AND token = 'gQTV7AWv7BNHg1uEVT4N+/OzPrJUs9OhVvNsbZuS7WU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}