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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1b82de4daa6d4ed5d738d4743a3d905a7dc69cecff9d5da6d920fd5fe642c8b' 
  AND token = 'W4sc1G+1jPlNxfeV4sxH0Q/UMCgBm3d6jSVl/wRcr2E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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