SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4e629b78760133604107f92583c305e38ac509612002f7a677c1bb19926cf69' 
  AND token = 'jf1vQXAUTj4yXfJHbUl0XYNnK7+xWVYySRffQZfBDdQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}