SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1773930fd9dd43c5f5a647d2eb3afc0d2c9b3c7d12c48042644c528183b2259' 
  AND token = 'dIi3cKLzVHK5xz6soGKfVJiVZ3GV1ZcgNVnIzu9nIlI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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