SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fdf10485e1e71cb45772760650fb328693c0dd77a804e0e305ce45e1ee38e375' 
  AND token = 'HEe1DAsIS4KaTq2lgIHcLRnBKLiTQdU0OahzOHffyn4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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