SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16af46f593f97d02ee06484b34ff8ef29552d34e92da979fe3ca2594c27b8296' 
  AND token = 'cDXvA/GamsdJkthh8VOLE+1RlT9kUzvBrn46VeOgK6s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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