SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b847c611b739f94bf155c7f269308cd51f751b071fab574c2cf2c717fcca23d3' 
  AND token = 'PN1LENUxfyG5GNpvqWXB5zxC9Sc49WTgv8IteayUKno=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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