SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6747346e52af7d56e315d5fa350b7eb6b0b9902da82be7e2f010a72a86ef7656' 
  AND token = 'AeNVJfLALoXdlsUNZaBVF/CiFl/iEmA+LeYGA75heM4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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