SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2acd838fbae4226f980438ea19c0047226382e582824b3de0af862c6ef1efb1a' 
  AND token = 'lelvlvimUU/IernoSdyFRgcTCVqvnp/pcWrkxAsF4zc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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