SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f28fb521b867f542fd9789ef25b59382ce4aa47a41c1a07334edca7acbf35292' 
  AND token = 'B7mRDnJkZP4KSaTygNbynAwxpy15W87zaUsv8nqyGLc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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