SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2e446d36791f77cbabbeffe50c1f856a36db53e35ca527af64213a15e7603a9' 
  AND token = 'yU4GTNNObAeOVMGPF3vYyvFX0Y6XT0ToCRohIACG1Uw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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