SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b493fe31595fb27defa8efe97175d168e10539a44a57feb2157ab663b83c5373' 
  AND token = 'G5PaSoQI1ToXPLuSTyPjzOaFa0R9+uJA6RjqzKg56yo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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