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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b57e159797f9fb3fbd42fc720f7b9f42e9ab2aeff3c1ab8fb58fab75bf743d40' 
  AND token = 'Sd7rdTTPG+SftByTOc/mnk11usPQw+4nl6XHn9MwrvQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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