SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e72c6d1b766278248d79a6f90c7fd1ac9a8f71e675c0dbf796ad5b43a936ba09' 
  AND token = '4r/gW+JyE8EhYCiNIXZBaUjCSYy+nCVliQpQBI8yIpQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}