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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78abd3b7ab02d9cf47d57c62caf037a931e5dd0568bde5e16d8d586faf74e15e' 
  AND token = 'gDRwpaZ+tqj8gdzp9gceVHzfr0FbJv6kV5MOjioLD3k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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