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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9f7be90c9ed1cb6d0322473ff4cca5efeafc57811ca6fc0a2a4b89746f4ef37' 
  AND token = '6hCaMNO7tOcLyjNlDvMBHVt4x/UQo3KvTab33fSdkNk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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