SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df782733802010ffc41ab73fc4be890b7a58466b36e2ec5ef8e875712dd61372' 
  AND token = 'pfPwMehcMiYcRK8eaTfH+d+6SnT6+s1ZpULfsdXV2HU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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