SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7377d6be9872f6a9b290a57f0957cc2993bc8512d3e0289df70a2a70848ad52e' 
  AND token = 'NY3E+zPH1tENQA4lWDxxnJVYv1o/FPNUsDEyaUCNakY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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