SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c2ff523ec1a6406255ebaeb69a2844f0b2eef595d63bc4cf9abedef1b9f97ef' 
  AND token = 'MRWInvXRzMcqx+LqZmxXwCPt8fagFw6+XLW7mRbUbCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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