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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7c394a75e36c40a96ea55c1f3c8e9464c2a7d5c655b31019f92e2c3ac8125d9' 
  AND token = 'qJ6Ry+EHbbim2ClDM5P8+isycYfhxKQP2MtXf3xDruI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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