SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '67bd88077abaf5883a71c0ce1133a34a93918233c630397018dc402236ad80f6' 
  AND token = 'kNzBlUXZTLD7otE2Mvn2Gumo6MYykuZcZxm30DcZyxM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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