SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4d72546626947eadf0112c2ad06bc8abf93eb0ac93a720927dac6c348035d2e' 
  AND token = 'gEro48iJKPS9HdSjF3+VZhH8262dqXIWHIcqmundIAk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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