SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '261dce30a3978521fedcd684dcf3f563b3790751f39a1b0152c136b702c5d5d1' 
  AND token = 'LHsNEsAAfosih3nRAbULlHaPs5M823Xm0esi91dDmU0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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