SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6511276a88778cc8513c042c3dce9f209279b11d4fe359d264fd1e631ec25b9' 
  AND token = '4vSTmKYnjUoYGhTXej5/gvpyl42oEcL9+KWSDH9lzNs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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