SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8606d21b35fa4c993d6653d4dae1f5db1c38cadc1f2a0fb462723c048271119' 
  AND token = 'Q+vkFP5W9GIzvEThYpSIcXRo7thFy+3qiflsFghNl+4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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