SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20015db4d797289628de4970ff723796342010f576e1f404647dd025891f4920' 
  AND token = 'Qt4yPJL2YU/ExHRCmOZFTUjL4uZwHuuHfuPyN5f6bPQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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