SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c99558b5e2e013b6c082e7949decbe2359acfdd5e0d968441a667c81699d9425' 
  AND token = 'lxQnyiHdVPXNKMiaFrvPAS2CY/JT6PDh7xinyG3n2+M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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