SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c27a6449550c161bad464f61051773dee0fea568c2c321cbbdbbafab274e966' 
  AND token = 'j3fW/UtzEOB7/21zcd1jKzzCY5edJnGZOxj0yTI6WS0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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