SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfba154af9f8c05df2b8662629f3346d0699a7d822ef5a30df30f43eef7a1074' 
  AND token = 'U2VmzCV1eTLM1lNBwpf7n6BZ2nb+lXsbPvYIKQjCSqs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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