SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c987c6f12f2b8151f161fd93000c62c68bcec29012c2bdb580a72639dbdaee7d' 
  AND token = 'gCAXyInmgK2z5vB6Ni3r6t/cqKIztAlMnO9umD08nYI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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