SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2f9eb69285c5726030e3d1016f0c361aa999df6ee177fc47b546e57a9729a57' 
  AND token = 'JMe3SyzEdQaCaaGzGMIMUGoVmFtSFMGGrFYG9T+BAjc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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