SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51451995e64f9be50f52aeda5b822fd38bf18b38b131f5152162f73ea58c1eaf' 
  AND token = 'GsEbbst+mX6EoeiL+YFbbYCxCq8nPWv7KJXmTxuuqNU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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