SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0b137b683430479c6d122187508c91ee8d475550eb2a2bae03e0bb44b038a6b' 
  AND token = 'RYmNpst2XDtHPn74tMYgAf4Y5r4jz+fFBHFnrImBpNU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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