SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75bc18678a0dbd0d3b91a7ca74ced90b6409c835743067ca9aab800bf772a45e' 
  AND token = 'Tk29rqx/okm8pnfh0OSflQfu+TOO40VCszCRtpq4DHU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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