SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7f8eff48cd79fa912a694eb77cd1bc156732a7670871d5b9675a52647029774' 
  AND token = '3JsDKGf9hmgdVYWHQ2Rz5fAVUFo3GKqjO0EASbFo6UA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00084

JSON explain

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