SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c75a997a4f19c2946ae5292b2a5e7fafa94d26268bbba10004927e1675894b87' 
  AND token = 'Xu67i2Msih873BWz2S1OIEOtiBJOK4k2JTDiYOMyt+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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