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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '252c983f5de0b8843ab725dbcc7c2e26174fbf9b01085be0b770ba092f2fc947' 
  AND token = '4ol5yjF/ZIvtt2bSnLInPCmgXOvMiFBU07BoWdzZsQA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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