SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '136abe0c477382f1a30841a4066321aba93c6a1af3d9d6e99f5a4a779ff93198' 
  AND token = '7BGrjzr9IoAT5JBUQg57Hsq2HnXyXA2LObigX8KtvO8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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