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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a501622ff8f3337f2d28d6b7b13ff7e38297777daed55f0a58d6fe4bb8ff7741' 
  AND token = '5yOnOIZQxW014I+j6waz7siAOWsIlTj1639Xrp0y7Zg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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