SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b52850b2ebcd3e21b0fd9a4a17a975059391f3188668fe51058597ae8cc243fd' 
  AND token = 'RotbALoZOB6VnaPQtwkhRDiTIXeBMp4Mu9vJrFIgn2E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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