SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '100cffad2030b62746e362a3557fea46b6a84897d10185e6c8cbf21364b38e2b' 
  AND token = 'seRm09BS8yLhNkZqEmuMNoFvisSLA36vYL3EGkaPhdA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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