SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '757a7d8455b9ccb935d93fbe1cc63a71034f4c7bf72e2bf4adbd401d9ac0f678' 
  AND token = 'HBlYda8iLfdtyjPmSJrbFHBVq9GxIs/q/BVCjCBisSE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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