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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2473b1bf5c030f775b975fb6862f840ee81ee76a3a388fd3e6a4715fa818a3a' 
  AND token = 'j9tSZf4tX4ifQga+tyqlIT0cK33lglALgxP9h3RPxjA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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