SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9f472ff4876a365664b2c578a19113b5a76cc3da7f6837797759d8bc1124608' 
  AND token = 'JbgP/qFPXXVpIUwAcKEL5UV31sJ80pWVFhvkW57rrP8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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