SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4428761d597981766e2b7a94198cbd0f7062f1ff1d65c74fc18bd0352e48e5f' 
  AND token = 'uzMjFsJoB+JY43izwKANlSVHAxnv/iQm5+EuxVN4HAg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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