SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef21b75784c11e182191b00c9c4996db92173edb1832f400054a4ec2a8f739d4' 
  AND token = 'DOrSM1M/gIiZIiGYPhuIfxqBzDmGz0WwCf3+GxpgEw8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}