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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6416259df516713a925f3b95903df0da5383e6ffc8c2e039289d2d5926cc0a3' 
  AND token = '3euFAsqrFzrYc/eaW42a8aMxrI/jZldBEHon6Bm2iPw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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