SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aec56126ac3e4a6e42c956a55cd9a242353eb34d9da7eb2046a5593b4312765e' 
  AND token = 'zbXzXnGBFDPN1D6fT5BDsRG2uW8zjCcBSCe7zhtSUU8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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