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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9d7f1dd6c245bfa53e1e43c1d0346045b0c607b18a30c0d4a7e5bada973d3fc' 
  AND token = 'SsXXaA8IcOxogQMWNTlhliBvYeWUSF4okOCzheXkxgk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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