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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4921eeb9bd674a15160bcbe2d2e3bafddbb3173300d15ddd20cba6f8b157db5' 
  AND token = 'CwS/UGKqK46AeysOdTcdhz2UFxdlt+FG1MBz4KYSNjg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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