SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c92df3f39b281685e49e69d497ba3363264d93df17a9d2bdb97563ebae49b38f' 
  AND token = 'U92zLV/v9u2/w1MlPiVJhm/x09Z08cSRbWHYDJZhRvY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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