SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '631a7cb00a61dfe3fb836cd561a83f403b557dee1267f6a7fd62d3fe401b3a7c' 
  AND token = '+SJURklEjR30jsIibitFqXJDttOcIF8jvCNnG58KInA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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