SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b71c9072cdf3bc60cdcfa88d836e9cff7950d19f863b4696fd58dc40e918645' 
  AND token = 'Ax2BMjxulfwAM18wBrsvRZMiD3r1/DlYKij2GE5CVDQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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